As an image recording apparatus for recording a medical image, such as a digital radiographic system, CT, or MR, a wet system in which an image is photographed or recorded on a silver salt photographic light-sensitive material, and then wet processed to obtain a reproduced image, has been conventionally used. In contrast, in recent years, a recording apparatus by a dry system using a photothermographic material (heat development recording apparatus) has attracted attention.
FIG. 6 shows a conventional example of this kind of a heat development recording apparatus.
The heat development recording apparatus 100 includes: a recoding material supply unit A accommodating sheet-like heat-developable recording materials 21; an image exposure unit B for performing an exposure processing based on image data on the heat-developable recording material 21 supplied from the recording material supply unit A; a heat development unit C for performing a heat development processing by a prescribed heating on the heat-developable recording material 21 which has gone through the exposure processing at the image exposure unit B; a cooling unit D for cooling and discharging the heat-developable recording material 21 which has gone through the heat development processing; a power source/control unit E for supplying a power to the respective units and controlling the operations of the respective units; and a transportation unit for feeding the heat-developable recording material 21 at the recording material supply unit A to the cooling unit D via the image exposure unit B and the heat development unit C sequentially (e.g., see, JP-A-2000-98576).
The heat-developable recording material 21 is prepared by providing a recording layer having light sensitivity and heat sensitivity on one side of a base film. Specifically, a photothermographic material or a light-sensitive heat-sensitive recording material is used according to the features of the recording layer.
The recording layer of the photothermographic material is a recording material which records an image thereon as a latent image by exposure with a light beam (e.g., a laser beam), and is then allowed to develop its color by heat development.
On the other hand, the recording layer of the light-sensitive heat-sensitive recording material records an image as a latent image thereon by exposure with a light beam, and then is heat developed and is allowed to develop its color, or records an image thereon by a heat mode (heat) of a laser beam, and simultaneously therewith, is allowed to develop its color, followed by image fixing thereon through light exposure.
In the recording material supply unit A of the example shown, recording paper accommodating cases (magazines) 15a, 15b, and 15c are disposed vertically at three stages. The respective recording paper accommodating cases 15a, 15b, and 15c are each capable of accommodating a large number (e.g., 150 sheets) of the sheet-like heat-developable recording materials 21 in stacked form. Then, feed roller pairs 13a, 13b, and 13c for feeding out and transporting the heat developable recording materials 21 in the cases, one by one, are provided at the outlet side of the respective recording paper accommodating cases 15a, 15b, and 15c, respectively.
The heat-developable recording materials 21 fed out from the respective recording paper accommodating cases 15a, 15b, and 15c by the feed roller pairs 13a, 13b, and 13c, respectively are fed to the image exposure unit B by a transportation unit 22 provided on the top end thereof.
The image exposure unit B includes: a transportation unit 27 having driving rollers 31 and 33 and a guide plate 35, and transporting the heat-developable recording materials 21 supplied from the recording material supply unit A at a prescribed speed; and a beam emission means 29 for performing scanning by a light beam (laser beam) 28 in a direction or thogonal to the transportation direction on the heat-developable recording materials 21 transported by the transportation unit 27. The scanning direction by the beam emission means 29 is set as a main scanning direction, and the transportation direction of the transportation unit 27 is set as a sub-scanning direction. Thus, the image exposure unit B performs main/sub-scanning by the light beam 28 on the recording layer of the heat-developable recording material 21 based on the recording image data supplied from an image information source such as CT or MR, thereby performing an exposure processing in accordance with an image to be recorded, and recording a latent image on the recording layer of the heat-developable recording material 21.
The heat development unit C is configured to include: a transportation unit 36 for transporting the heat-developable recording material 21 subjected to the exposure processing at the image exposure unit B through an arc-like path; and a heating unit 37 provided along the transportation path by the transportation unit 36, for performing a prescribed heat processing on the recording layer of the heat-developable recording material 21 being transported by the transportation unit 36.
The transportation unit 36 transports the heat-developable recording material 21 through the arc-like path by a plurality of presser rollers 41 driven in rotation following a gear 43, and a supply roller pair 39 disposed closer to the image exposure unit B.
The heating unit 37 is configured to include a plurality of plate heaters 37a, 37b, and 37c arranged along the arc-like transportation path of the transportation unit 36. The heat-developable recording material 21 is transported with the recording layer facing the side of the plate heaters 37a, 37b, and 37c. 
The foregoing heating unit 37 increases the temperature of the recording layer of the heat-developable recording material 21 to a prescribed heat development temperature (e.g., 120° C.), thereby to develop/fix the latent image recorded on the heat-developable recording material 21 as a visible image with a prescribed concentration.
The cooling unit D is mounted partway along a discharge-side transportation route 50 extending horizontally from the terminal end of the heat development unit C, and cools the heat-developable recording material 21 after the development processing supplied via a delivery roller 45 by heat dissipation during transportation by means of an appropriate number of cooling roller pairs 47 to an appropriate temperature such as ordinary temperature.
The cooled heat-developable recording material 21 is discharged to a discharge tray 17 via an inducing path by a guide plate 49 and a transportation roller pair 51.